1. Field of the Invention
The present invention specifically relates to a connection terminal unit for an antenna, which is suitably used to connect a film antenna provided on a window in an automobile or the like.
2. Description of the Related Art
Recently, many automobiles, notably luxury cars have employed a film antenna composed of an antenna element pattern printed on a transparent film, in place of a rod antenna.
The film antenna is provided on, for example, the inner surface of a rear or side window. Further, various antennas are designed and sold in order to receive FM broadcasts, FM-VICS broadcasts (FM multiplexed broadcasts that provides service information for navigation systems), GPS (Global Positioning System) signals, TV VHF/UHF broadcasts, and the like. The film antenna is superior to the rod antenna, which projects out of the car, in that its wiring has only to be laid inside the car, in that it is esthetically more excellent because it involves nothing projecting inside a passenger room or out of the car, and in that it is unlikely to encounter tampering or the like.
A connection terminal unit is attached to a tip of a connection cord connected to a connection terminal pattern of the film antenna in order to load signals received by the antenna. A pressure sensitive adhesive double coated tape is provided on the back surface of the connection terminal unit so as to cover the entire surface. A connection terminal portion is arranged in a central portion of the pressure sensitive adhesive double coated tape in its central portion so as to be drawn out from the connection terminal unit. The connection terminal portion is electrically connected to the film antenna.
In such a connection terminal unit, the connection cord is guided into a resin case of the connection termination section via an opening formed in one side wall of the case. One end of the connection terminal unit is electrically connected to the tip of the connection cord by, for example, soldering.
On the other hand, an adhesive is filled into the case and then hardened to prevent air, moisture, or the like from entering the interior of the case.
Furthermore, a resin cover is fitted on the case, the resin cover having a U-shaped notch formed in association with the connection cord. The connection terminal unit thus has a box structure.
This makes the connection terminal unit unlikely to be deformed in spite of external force to prevent the entry of external moisture.
Further, some connection terminal units are known which are entirely covered with a mold member made of an insulator resin such as an ABS resin or an AES resin with only the other end of the connection terminal unit exposed.
Most windows in automobiles to which the film antenna is attached, notably front and rear windows have curved surfaces instead of flat surfaces. Accordingly, the film antenna and its connection terminal unit are desirably flexible enough to be attached to the window along its curved surface. Therefore, a sufficiently thick and elastic film antenna must be employed if it is attached to a curved surface.
Further, such a connection terminal unit generally corresponds to a solid wire. However, the solid wire corresponds only to a signal line to the antenna. This hinders an earth line from being simultaneously connected to the antenna.
If the antenna has only the signal line and no earth lines, an antenna signal received via the signal line is likely to be affected by noise. It is contemplated that an earth line may be separately connected to the antenna. However, this results in a complicated structure and increases manufacturing costs.